[Equest-users] Thermostat setpoint quandry

[Erik Kolderup]

Vikram,

The original file you posted had constant 55F supply air temperature. So
combined with constant airflow it was driving the zone to the heating
setpoint.

If the supply air temperature control is changed to "warmest" then the
space temperature will vary a bit, moving between the heating and cooling
setpoints. I haven't looked closely at your model and I'm not sure what
climate you're modeling, but it wouldn't be unusual to be at the cooling
setpoint at times in the winter. The space should be in cooling mode
whenever the outdoor temperature is above the balance point temperature. I
would expect it to be at the heating setpoint only when either the outdoor
air temperature is below the balance point or if the combination of supply
air temperature and minimum airflow is overcooling the zone.

I often find it useful to report the supply air temperature as an hourly
variable to check that DOE2 is doing what I expect.

-Erik

*Erik Kolderup, PE, LEED AP*
erik at kolderupconsulting.com | 415.531.5198 | www.kolderupconsulting.com

On Tue, May 19, 2015 at 4:30 PM, Sami, Vikram <vikram.sami at zgf.com> wrote:

>  Thanks Erik.
>
>
>
> Now what if it’s a scenario where the room has a minimum airflow
> requirement (like a lab or an operating room)? I would have thought
> resetting the supply air temp would settle the issue.
>
>
>
> Also  - when I reduce the airflow rates, it still doesn’t behave well – I
> get cooling temperature setpoints in the winter.
>
>
>
> *Vikram Sami*
> AIA, BEMP, LEED BD+C
> Associate Partner
>
>
>
> ZGF ARCHITECTS LLP
> *T *206.521.3509 *E *vikram.sami at zgf.com
> 925 Fourth Avenue, Suite 2400
> Seattle, WA 98104
>
>
>
> *From:* erik.kolderup at gmail.com [mailto:erik.kolderup at gmail.com
> <erik.kolderup at gmail.com>] *On Behalf Of *Erik Kolderup
> *Sent:* Monday, May 18, 2015 5:06 PM
> *To:* Sami, Vikram
> *Cc:* equest-users at lists.onebuilding.org
> *Subject:* Re: [Equest-users] Thermostat setpoint quandry
>
>
>
> Vikram,
>
>
>
> I suggest checking your minimum airflow schedule ("Annual Schedule
> Airflow"). Looks like the values are greater than one, resulting in a
> constant volume system that gets driven to the heating setpoint. If the
> airflow were allowed to drop then there would probably be hours at the
> cooling setpoint.
>
>
>
> Regards,
>
> Erik
>
>
>   *Erik Kolderup, PE, LEED AP*
>
> erik at kolderupconsulting.com | 415.531.5198 | www.kolderupconsulting.com
>
>
>
> On Mon, May 18, 2015 at 3:51 PM, Sami, Vikram <vikram.sami at zgf.com> wrote:
>
>  I’m a little stumped here.
>
>
>
> I’m running a simple single zone VAV simulation that has a setback
> temperature schedule for heating and cooling seasons. For some reason, if
> you examine the hourly report, it seems to use the heating schedule for the
> entire year (inp file attached).What am I missing?
>
>
>
> Any insight would be much appreciated.
>
>
>
>
>
> *Vikram Sami*
> AIA, BEMP, LEED BD+C
> Associate Partner
>
>
>
> ZGF ARCHITECTS LLP
> *T *206.521.3509 *E *vikram.sami at zgf.com
> 925 Fourth Avenue, Suite 2400
> Seattle, WA 98104
>
>
>
> ZGF Email Disclaimer <https://www.zgf.com/ZGF_Email_Disclaimer.html>
>
>
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